It is well known in the heating, cooling, and ventilating industry that outside air must be introduced into a building to eliminate contaminants and odors, at least in commercial environments, during periods of high occupancy or the industrial production of contaminants. Large industrial dampers are provided to meet these requirements and must be of substantial size to handle elimination of the maximum of contaminants which may be produced at any time. Commonly such ventilation systems have control systems which intermittently open and close the outside air dampers in order to provide sufficient outside air to adequately dilute the contaminants inside a building; however, during time periods when an industrial building is unoccupied or the creation of contaminants is relatively low, the control system is designed to close the outside air dampers.
Most industrial dampers consist of vanes having a length of four feet and a width of approximately five inches. A vertical array of a sufficient number of vanes to close a ten to fifteen foot high opening of four foot width is not uncommon in industrial facilities of even moderate size. In some instances a plurality of such four foot wide arrays of dampers may be employed in order to achieve the ventilating capability required for a particular system depending upon the building size and the quantity and types of contaminants that are created.
For the most part these air dampers have a plurality of vanes which are pivotally mounted medially of the width thereof. A periphery of the width of the vanes characteristically has a flange formed therein for interfitting with a groove of an adjacent vane when the air damper is closed. The spaces between vanes and laterally thereof can commonly cause air leakage on the order of fifteen percent of the air input which would be experienced without the use of a damper seal. In many areas of the country where the outdoor night temperature averages on the order of 30.degree. F. for approximately one-half of the year, the heating cost to offset the 15% air leakage can easily amount to thousands of dollars for even a moderate sized damper installation. When the pivots of the vanes or other mechanical components experience wear over a period of time larger spaces between vanes frequently permit even greater air leakage heat losses.
It has been found that by effecting a relatively efficient seal between the damper vanes the 15% air leakage can be reduced to an approximately 3-5% leakage rate. Such a 10-12% reduction in the air leakage rate of a damper translates to heating cost savings on the order of several thousand dollars per heating season for 80,000 to 100,000 cubic feet per minute air handling systems in many portions of the country.
In recognition of the potential savings in heating costs, some extent of effort has been directed toward the creation of more effective seals between vanes. In one form or another these efforts have been directed toward providing some type of sealing element in the grooves positioned at the periphery of the width of the vanes and particularly in the interfitting portions between the flanges and the grooves of adjacent vanes. In some instances a thin strip of foam has been cemented or bonded in the groove in order to effect engagement with the flange of an adjacent vane. In other instances sealing strips may be employed which are attached to an inside portion of the flanges and have a projecting member which extends between portions of the mating flange and groove to effect a sealing relationship. The projecting portions of such sealing strips may consist of a wiper like member or an enlarged bubble of foam or comparable material. In these instances the sealing strips are attached interiorly of the flanges and have the sealing element projecting into the mating groove area to effect a seal thereat.
While many damper sealing systems may be relatively effective when first installed, most are susceptible to significant operating problems after they have been subjected to an extent of usage and the outdoor environment. In many instances the operating system for the vanes may produce sufficient play such that the sealing strips are no longer totally effective. In other instances the deterioration of the seals may preclude the sealing engagement between the flange and groove so that the efficiency gains are no longer realized. In many instances, particularly where the sealing elements are cemented or bonded in place, the removal and replacement of the seals has proven to be a relatively difficult and expensive form of maintenance. No single sealing system employed to date has demonstrated an ability to have and maintain a high operating efficiency while being capable of easy removal and installation.